Actually I'd say you have good auto mechanic skills, just a bit green (lack of knowledge).

Look at the power flow diagrams on this page
http://www.heritech.org/cuda/Charge.html
This will help you understand most of the things you observed.

At the bottom is a simplified '67 wire diagram of the charge and ignition.
Your '71 will be similar except for a couple of things.
Of the top of my head, the alternator field circuit on your '71 will not ground internally. Instead it will have a ground wire coming back to the voltage regulator.
Also not shown in my '67 wire diagram is that engine instrument gages have a voltage regulator so the sending units all get 5 Volts.